GB/T 3108-1999 Impressed current cathodic protection system for hulls
Some standard content:
ICS 47. 020. 05
National Standard of the People's Republic of China
GB/T3108—1999
Impressed current cathodic protection system for ship hull
Impressed current cathodic protection system for ship hullIssued on August 31, 1999
Implementation on June 1, 2000
Issued by the National Quality and Technical Supervision Commission
GB/T3108·1999
This standard is a revision of GB/T3108—1982Impressed current cathodic protection system for ship hull. The main technical differences between this standard and GB/T3108-1982 are as follows: the two important parameters of the protection potential range and protection current density of the hull steel plate are modified: the protection current density of the propeller, rudder and city deflector is added; three new auxiliary anode materials, platinum-phosphorus composite materials, platinum-phosphorus composite materials and titanium-based metal oxides are added; the technical indicators of the insulation performance and watertightness performance of the auxiliary anode and reference electrode are added; Chapter 4 - Design of external current cathodic protection system is added.
This standard deletes the specific specifications, models and structural drawings of the auxiliary anode and reference electrode in GB/T3108-1982, deletes the series specifications of the marine phase potential only, and deletes Appendix A "Design and Series" and Appendix B\Model Description of Auxiliary Anode and Reference Electrode". This standard will replace GB/T3108-1982 from the date of implementation. Appendices A and B of this standard are standard appendices. Appendices C and D of this standard are standard appendices. Appendix of the reminder. This standard was issued by the Technical Committee on Application Technology of Marine Materials of the National Technical Committee for Standardization of Marine Ships. This standard was issued by the Luoyang Ship Material Research Institute of China State Shipbuilding Corporation. This standard was drafted by the Luoyang Ship Material Research Institute of China Shipbuilding Industry Corporation and the Ministry of Transport's E-Marine Ship Transportation Science Research Institute. The main drafters of this standard are Tu Langchen, Wang Zaizhong, Xu Likun, Li Guihua, Gao Yuzhu, Xu Jianhua, Dong Chaoying, Chang Ninghui, and Dian Kexian. This standard was first issued in May 1982. 1 Scope
National Standard of the People's Republic of China
Inipressed curreat cathodic protection system For ship hullGB/1 3108—-1999
代#/108—19B2
This standard specifies the requirements, system design, test methods and inspection rules for impressed current cathodic protection systems. This standard applies to the design and inspection of impressed current cathodic protection systems used by glass blocks in the submerged parts of the hull of steel seagoing vessels. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. The versions shown are valid when this standard is published. All standards All of them will be revised. All parties using this standard should discuss the possibility of using the latest version of the following requirements. GB/T7387-1999 Technical conditions for reference electrodes for cabins GB/T7388-1999 Technical conditions for auxiliary anodes for ships GB/T7788-1987 General technical conditions for anode screen coatings for ships and marine engineering CB-3220-1984 Technical conditions for constant potential apparatus C1B/T3455-1992 Design and installation of anode screens for ships 3 Requirements
3. 1 Protection potential range
The protection potential range of hull steel plates should usually reach -0.80~1.00V (relative to silver/silver oxide reference electrode/water). Under special circumstances, when the anode arrangement position is not controlled, the protection potential range can be -0.75~! The value of the hull protection potential can be found in Appendix A (Standard Appendix) A1, which is -1.00 V. Using different ratio electrodes
3.2 Tracking performance
When the ship's speed changes and the given potential changes, the output voltage and output voltage of the constant potential instrument should also change accordingly and make the hull reach the protection potential range.
3.3 Constant potentiostat
3.3.1 Constant potentiostat should be able to work reliably under the following environmental conditions: a) Ambient temperature: -10~～55℃, b) Relative air humidity is greater than 95%; c) There is condensation, salt spray, oil mist and mold, etc.; or) The power supply variation range is ±10% in steady state and ±20% in transient state (recovery time 3s); e) Motion: 2~13, 2 Hz+ displacement 1 ram13. 2~ 80 Hz; Speed: + G. 86 m/s*; e) Pitch, horizontal angle 22.5°, pitch, vertical angle 10%. 3.3.2 The constant potential instrument shall have the following performances:) Input impedance not less than 1M; h) Potential control setting error not less than -F0,02 V; Approved by the State Administration of Quality and Technical Supervision in 1999-08-3T and implemented in 2000-06-01; c) Continuously adjustable within the given potential range; d) Manual and automatic control; e) Half-load ripple factor not more than 10%; t) Current limiting or overcurrent protection. 3.3.3 The constant potential instrument shall have the following detection functions: a) Total input current; b) Output voltage; c) Given potential; d) Hull potential.
GB/T 3108—-1999
3.3.4 The potentiostat should have a drip-proof, interference-proof metal structure shell, and the shell protection type is IP223. 4 Auxiliary resistor
The auxiliary anode should have good conductivity, large output current and long service life. : 3.4.1 Types and main properties of materials
The types of commonly used auxiliary anode materials include lead-silver alloy, silver-plated platinum, platinum-plated titanium, platinum-titanium, platinum saw and titanium-based metal oxides, and their main properties should meet the requirements of GB/T7388.
3.4.2 Shape
The auxiliary anode should be in the shape of a long strip, or a disc. 3.4.3 Insulation performance
The insulation resistance between the anode or conductive rod and the anode stuffing box or watertight cover should be greater than 1 Mn in a dry state (i.e. before the water pressure test after the anode structure is installed).
3.4.4 Water tightness performance
The water tightness of the anode cover should not be leaking for 15 minutes under a water pressure of 196 kPa. 3.5 Anode shield layer
3.5.1 Coating
The technical indicators of the anode shield coating should meet the requirements of GB/T 7788. 3. 5.2 Shape
The shape of the anode shielding layer corresponds to the shape of the auxiliary anode. 3.5.3 Size measurement
For the calculation method of the size of the anode shielding layer, see Appendix B (Standard Appendix). 3.5.4 Cathode potential resistance value
Ensure that the hull potential at the edge of the anode shielding layer is not higher than the cathode potential resistance of the hull coating (referring to the absolute value). The cathode potential resistance values of various hull coatings are shown in Appendix ((Suggestive Appendix)) 3.5.5 Thickness
The thickness of the anode shielding layer should be determined according to the shielding layer life requirements and the performance of the anode shield coating. Usually, it should be thicker near the auxiliary anode insulation seat and gradually thinner towards the edge of the shielding layer. The edge should be as thin as 0.5 mm. Its coating should comply with GB/T 3455 3.5.6 Lifespan
The design lifespan of the anode shield is 6~~10a. 3.6 Reference electrode
The reference electrode should have small polarization, stable performance and long lifespan. 3.6.1 Types and main performances
The types of Denby electrodes are silver/silver fluoride electrode/seawater, zinc and zinc alloy electrode/seawater, and their main performances should meet the requirements of CB/T7387.
3.6.2 Insulation performance
CB/↑ 3108—1999
When the reference electrode is in a dry state, the insulation resistance between the electrode body or conductive rod and the electrode watertight cover or stuffing box should be greater than 1M. 3.6.3 Watertight performance
The watertightness of the zero ratio electrode structure. Under a water pressure of 196kPa, it lasted for 15 min should be water seepage, 3.7 Grounding device of rudder and propeller shaft
3.7.1 Grounding device of energy
To prevent electrochemical corrosion of energy blades, a single-core marine soft electric rod with a cross-sectional area of not less than 25 mm\ should be used in the steering gear cabin. The short-circuit grounding resistance between the energy column and the hull should be less than 0.02 2.
3.7.2 Grounding device of propeller shaft
3.7.2.1 When the propeller shaft grounding device is used, the potential difference between the propeller and the hull should be reduced to less than 0.1V to avoid electrochemical corrosion. 3.7.2.2 The propeller shaft grounding device is mainly composed of a conductive ring, an electric steel, a brush holder and a support frame. Its structure is shown in Appendix D (Appendix D1).
3.7.2.3 The conductive ring is generally made of yellow steel into two semi-circular slip rings, which are then fastened with bolts. It can also be made of silver-steel bands into a conductive ring, with both sides tightened.
3.7.2.4 The brush is usually made of stone. Generally, a set of propeller shaft grounding device is equipped with three brushes, one of which is used to measure the potential difference between the frequency of the propeller and the hull. The brush should be insulated from the hull. 3.7.2.5 The installation position of the propeller shaft grounding device should be selected in a wide, oil-free, easy to observe and maintain position. 4 Design of the external cathodic protection system
4.1 Calculation of the protection area
4.1.1 The hull flooding area can be accurately calculated according to the line diagram. 4.1.2 The hull flooding area can also be calculated approximately according to formula (1). S+ - 1.7TLW + V/T
Wherein, S.-hull flooding area, m*
T\Full load draft, m
Lw!--full load waterline length, m;
V-full displacement volume, m\,
4.1.3 The propeller surface area is calculated according to formula (2). nan+nndL
Wherein: S:
propeller surface area, m
r—propeller diameter
d.—-propeller diameter m;
——propeller expansion disk ratio!
d.---shaft diameter, m;
1. Shaft length·tangent.
4.1.4 The actual dimensions of the rudder or other appendages are used to calculate the area S., S. respectively. 4.2 Selection of protection current density
The protection current density is related to the material of the hull, the surface coating condition, the ship's navigation rate, speed, dry docking time and water quality. In design, the protection current density is usually selected according to Table 1. For special ships, the protection current density can be appropriately increased according to their working conditions and the length of the allowable maintenance interval.
W Fuel
External plate www.bzxz.net
Propeller
Product guide
4.3 Total protection current required for the whole ship
B/T 3108 --1999
Table 1 Protection current density
Copper, brass
The total protection current required for the whole ship is calculated according to (3). Surface condition
I =i+$1 + tz+S,+ t-Sa +i, +S.
Total protection current density required for the whole ship, A;
i--~-Protection current density of the hull, A/m\, i.—·Protection current density of the propeller, A/mi—--Protection current density of the energy source, A/m,
Protection current density of other appendages, A/m. 4.4 Selection of constant potential instrument, auxiliary anode, multi-potential instrument Protection current density, mA/m
4.4.1 According to the total protection current of the whole ship, select the specification of the potentiostat according to CB'3220. When natural-based auxiliary anode is selected, the rated output DC voltage of the constant potential instrument shall not exceed 12 V. 4.4.2 According to the total protection current required by the whole ship, the ship's tonnage, the requirements of the overall design of the ship and the service life of the auxiliary electrodes, the specifications and number of the anodes (generally an even number) shall be selected in accordance with GB/7388. 4.4.3 According to the overall design requirements, the tonnage of the ship and the number of installations of the constant potential device, the type and number of the multi-potential electrodes shall be selected in accordance with GB/7388. In principle, the number of multi-potential electrodes installed on a ship should not be less than two. 4.4.4 According to the overall requirements of the ship and the type of auxiliary electrodes, the size of the anode shielding layer shall be calculated in accordance with Appendix B (Appendix of the Standard).
4.5 Selection of cables
4.5.1 The cables used in the externally impressed protection system shall be electric cables. 4.5.2 The conductor cross-section of the auxiliary electrode cable shall be large enough to make the line voltage from the constant potential device to the sink terminal less than 2 V, and the line voltage of each resistor as close as possible. 4.5.3 The voltage drop of the grounding electrode should be less than 0.1 V. 4.5.4 The cable of the reference electrode should be a shielded cable. 4.6 Principles of the arrangement of auxiliary anodes and reference electrodes 4.6.1 The total arrangement of auxiliary anodes should be such that the potential of the anodes can reach the protection potential specified in 3.1. 4.6.2 Longitudinal arrangement of auxiliary anodes: Arrange them on the upper, lower and lower parts of the ship, preferably on the lower part. If the installation is difficult, they can be arranged on the lower part of the ship or only on the lower part of the ship, but the arrangement should be symmetrical on the left and right. 4.6.3 Vertical arrangement of auxiliary anodes: From the heavy waterline to the center line of the bottom, it should be about one-tenth of the length, but it must be less than 5 m below the light waterline.
4.6.4 Longitudinal arrangement of reference electrodes: If two reference electrodes are installed on the whole ship, in principle, one on the upper part and one on the lower part or the lower part, and it is best to configure them separately on the right and left sides. If two reference electrodes are installed, in principle, two should be provided at the front and rear of the ship, separated on the left and right sides. The specific location is preferably near the screen near the anode between the two auxiliary electrodes. 4.6.5 The reference electrode should be arranged in the same horizontal plane as the auxiliary anode. 4
W5 Test method
5.1 System test
GB/T 3108 -1999
5.1.1 After the ship is launched into water (seawater or line seawater), before the impressed current cathodic protection system is energized, the reference electrode installed on the hull shall measure the natural electrode potential of the vessel.
5.1.2 After the impressed current cathodic protection system is powered on, a reference electrode installed on the body is selected as the control electrode, and three different applied voltage values are selected within the protection voltage range, and the changes in voltage, output current and body potential of the constant potential instrument are recorded at different given potentials:
5.1.3 After the impressed current cathodic protection system is powered on, 100 million points are selected on both sides of the ship to measure the protection voltage of the body.
5.2 Navigation test
During the operation of the impressed current cathodic protection system, the reference electrode installed on the ship is used to pull the body at different speeds and the constant potential instrument is used to extract the changes in voltage and output current.
6 Inspection rules
6.1 During the ship mooring and navigation tests, the hull potential and the operation of the constant potential instrument shall be inspected. The inspection items are shown in Table 2 and Table 10. Inspection items
Inspection items
Protection potential
Tracking performance
Inspection rules
5. 1. 2.5, 1- 8,5. 2
5. 7. 2,5, 2
6. 2 During the ship mooring and navigation tests, no matter how the external conditions change, the hull protection potential and the constant potential instrument tracking performance meet the requirements, which shows that the impressed current protection system is reasonably designed and works properly. GB/T 3108--1999
Appendix A
(Appendix of the standard)
Corresponding relationship of the potential of the hull to different reference electrodesA1 The corresponding relationship of the potential of the hull to the non-mesh reference electrode is shown in Figure A1. Silver/oxidation electrode/seawater
Steel/saturated sulfur rubber pin electrode
Zinc electrode/seawater
Figure A1 Corresponding relationship of the potential of the hull to different reference electrodes Appendix B
(Appendix of the standard)
Design and calculation method of the size of the anode shielding layerB1 The schematic diagram of the circular anode shielding layer is shown in Figure B1, and its radius is calculated using formula (L1). Auxiliary plate
Figure 131 Schematic diagram of circular anode shielding layer
2 yuan (F — E)
In the play:-
Radius of circular anode shielding layer,:
-Rated output current of auxiliary anode.A;
Protection potential range
.+--+.+
...-( B1 )
W Seawater resistivity,·mt
GB/T 3108-1999
Minimum protection potential of hull in seawater (absolute value), VEmin
E--The body potential at the position away from the center of the auxiliary anode, V, which depends on the cathode potential value of the coating at the lower part of the hull. B2 Schematic diagram of long strip anode shielding county See B2, its size is calculated according to formula (B2). Anode quasi-magnetic material
Lizard species liver plate
Figure 12 Schematic diagram of long strip anode room island
Formula: 1
The length of the long strip auxiliary pole, m2;
L.(Em—E)
The distance from the edge of the shielding layer to the auxiliary pole line, machine! The rated output current of the auxiliary anode, person, sea seek training resistance,·n!
--Minimum protective potential of hull in seawater (absolute), V+
++++++++++++++++++++(H2 )
The hull potential at the auxiliary anode axis &, V: It depends on the cathodic resistance potential value of the underwater part of the hull, Appendix
(record of indications)
Cathodic resistance potential value of hull coating
C1 The cathodic resistance potential values of various hulls are shown in Table C1. Table C1 Cathodic Ionization Potential Values of Various Coatings Type of Coatings
Asphalt-based coating
Ethylene-based coating
Chlorinated rubber-based coating
Epoxy-based coating
Organic high-grade coating
Non-conductive coating
Epoxy-polyester coating
Low cathodic resistance, V
WGB/T3108—1999
Appendix D
(Appendix for reference)
Structure diagram of propeller shaft grounding device
b1 The structure of the propeller shaft grounding device is shown in Figure D1. 1-brush grip; 2-fixed screw; 3-support frame; 4-slip ring; 5-braided ring; 16-measuring wire; 7-measuring cable; 9-propeller; 10-radiator; Figure T1 Structure diagram of the propeller shaft grounding device
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